Pteridophytes

• Pteridophytes

  Include horsetails & ferns
• Pteridophytes

  • Found in cool, damp, shady places
  • First terrestrial plant to possess vascular tissue-xylem & phloem
  • Used for medicinal purpose & soil-binders
  • Main plant body diploid (2n) sporophyte
  • Sporophyte is differentiated into true root/stem/leaf
  • Have Antherozoids in Antheridia & Egg in Archegonia
  • Also require water for fertilisation
• Types of leaves

  • Microphylls (small) - Eg: Selaginella
  • Macrophylls (large) - Eg: Ferns
• Prothallus

  • Inconspicuous, small
  • Multicellular
  • Free-living
  • Photosynthetic thalloid gametophyte (n)
• Sporangia produce spores by meiosis in spore mother cells
• Haploid spore develops into prothallus (n)
• Development of zygote into young embryo takes place within the female gametophytes
• This event (development of zygote into young embryo within female gametophyte) is a precursor to the seed habit and considered as an important step in evolution
• Female gametophyte is retained on parent sporophyte for variable periods
• Classes of Pteridophytes

  • PSILOPSIDA - Psilotum
  • LYCOPSIDA - Selaginella, Lycopodium
  • SPHENOPSIDA - Equisetum
  • PTEROPSIDA - Dryopteris, Pteris, Adiantum
• Selaginella is Heterosporous
• Equisetum is Homosporous
• Lycopodium is Homosporous
• Male spore (n) is microspore, Female spore (n) is megaspore
• Male gametophyte (n), Female gametophyte (n)
• Spore


  Terminates prothalles
• Pteridophytes


  • Include horsetails and ferns
  • Used for medicinal purposes and as soil-binders
  • Frequently grown as ornamentals
  • Evolutionarily the first terrestrial plants to possess vascular tissues - xylem and phloem
• Pteridophytes


  Found in cool, damp, shady places though some may flourish well in sandy-soil conditions
• Bryophytes


  Dominant phase in the life cycle is the gametophytic plant body
• Pteridophytes


  Main plant body is a sporophyte which is differentiated into true root, stem and leaves
• Leaves in pteridophyta


  • Small (microphylls) as in Selaginella or large (macrophylls) as in ferns
• Sporophytes of pteridophytes


  1. Bear sporangia that are subtended by leaf-like appendages called sporophylls

  2. In some cases sporophylls may form distinct compact structures called strobili or cones (Selaginella, Equisetum)

  3. Sporangia produce spores by meiosis in spore mother cells

  4. Spores germinate to give rise to inconspicuous, small but multicellular, free-living, mostly photosynthetic thalloid gametophytes called prothallus
• Prothallus


  Require cool, damp, shady places to grow<|>Because of this specific restricted requirement and the need for water for fertilisation, the spread of living pteridophytes is limited and restricted to narrow geographical regions
• Gametophytes of pteridophytes


  1. Bear male and female sex organs called antheridia and archegonia, respectively

  2. Water is required for transfer of antherozoids - the male gametes released from the antheridia, to the mouth of archegonium

  3. Fusion of male gamete with the egg present in the archegonium result in the formation of zygote

  4. Zygote thereafter produces a multicellular well-differentiated sporophyte which is the dominant phase of the pteridophytes
• Homosporous pteridophytes


  Produce all similar kinds of spores
• Heterosporous pteridophytes


  Produce two kinds of spores, macro (large) and micro (small) spores
• Heterosporous pteridophytes


  1. Megaspores and microspores germinate and give rise to female and male gametophytes, respectively

  2. Female gametophytes are retained on the parent sporophytes for variable periods

  3. Development of the zygotes into young embryos take place within the female gametophytes
• Classes of pteridophytes


  • Psilopsida (Psilotum)
  • Lycopsida (Selaginella, Lycopodium)
  • Sphenopsida (Equisetum)
  • Pteropsida (Dryopteris, Pteris, Adiantum)
• The gymnosperms and angiosperms produce haploid microspores and megaspores which develop into male and female gametophytes, respectively